There has been considerable concern that diets high in refined carbohydrates promote human disease and obesity. Laboratory research has documented that high carbohydrate diets increase caloric intake, body weight, and body fat in animals, but the mechanisms responsible for these effects are not completely understood. New findings from my laboratory have revealed further complexity in carbohydrate appetite. First, we discovered that rats and other species have a taste and appetite for starch-derived polysaccharides distinct from their taste for sugars. Second, we demonstrated that the postingestive actions of carbohydrate can condition extremely strong flavor preferences even for normally avoided tastes (bitter, sour). The goal of this proposal is to further elucidate the postingestive conditioning of appetite by carbohydrates and to assess the impact of carbohydrate taste and conditioning on long-term energy balance. The specific aims of the project are to (1) Evaluate the nutritive unconditoned stimulus (US) in carbohydrate appetite conditioning. The effect of carbohydrate type, concentration, and rate of infusion on conditioning will be determined. (2) Determine the site(s) and mute(s) of action of the carbohydrate US. Gastric, intestinal, and hepatic sites, and neural and hormonal routes will be investigated. (3) Evaluate the orosensory conditioned stimulus (CS) in carbohydrate conditioning. The role of olfactory and gustatory cues, and CS palatability in carbohydrate conditioning will be determined. (4) Investigate the behavioral and physiological processes associated with carbohydrate conditioning. Conditioning effects on ingestive patterns, the cephalic insulin response, and central neural coding of taste will be investigated. Also, carbohydrate conditioning and protein conditioning will be compared as will flavor-flavor and flavor-nutrient conditioning. (5) Determine the influence of carbohydrate taste and conditioning on long-term caloric intake, body weight and adiposity. This research, which involves the fields of psychobiology, nutrition, and gastrointestinal physiology, will provide new information on the interaction of taste and nutrition in the control of food selection, caloric intake, and body weight and adiposity.